/**
 *    Copyright (C) 2024-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#pragma once

#include "mongo/bson/bsonobj.h"
#include "mongo/db/admission/execution_control/execution_admission_context.h"
#include "mongo/db/admission/ingress_admission_context.h"
#include "mongo/db/operation_context.h"
#include "mongo/util/duration.h"
#include "mongo/util/modules.h"

namespace mongo {
/**
 * TicketHolderQueueStats should only be constructed from a completed operation. It retrieves
 * queueing statistics for the operation and stores them so they can be accumulated with future
 * operations (for transactions) or serialized and outputed to the user. Statistics are outputted
 * in slow query and slow transaction logging.
 */
class MONGO_MOD_PUBLIC TicketHolderQueueStats {
public:
    enum class QueueType { Ingress, Execution };

    TicketHolderQueueStats() = default;

    /**
     * Uses the AdmissionContext on the OperationContext to populate stats for both
     * ingress and execution control queues.
     */
    TicketHolderQueueStats(OperationContext* opCtx);

    /**
     * Serializes to BSON for use in slow query logging. Any k/v pairs
     * where the value is zero will be omitted from the output.
     */
    BSONObj toBson() const;

    /**
     * Aggregates queueing statistics on this instance by adding values from otherQueueStats. Used
     * to accumulate metrics across operations in a transaction for slow transaction logging.
     */
    void add(const TicketHolderQueueStats& otherQueueStats);

    static std::map<TicketHolderQueueStats::QueueType,
                    std::function<AdmissionContext*(OperationContext*)>>
    getQueueMetricsRegistry();

    static std::string queueTypeToString(QueueType queueType) {
        switch (queueType) {
            case QueueType::Ingress:
                return "ingress";
            case QueueType::Execution:
                return "execution";
            default:
                MONGO_UNREACHABLE;
        }
    }

private:
    struct Stats {
        int admissions = 0;
        long long totalTimeQueuedMicros = 0;
    };

    std::map<QueueType, Stats> _statsMap;
};

}  // namespace mongo
